Preposition stranding

A follow-up to "My aunt, who I live with"

People are advised not to end a sentence with a preposition.
"Preposition" has to be "pre-positioned," not "post-positioned." This is literally what the preposition is about. (I end this with "about," though...)

In fact, this so-called "prepositional stranding" is often taken up as one of the grammar usages that people tend to avoid when they write formally. In case of casual conversation, few people would tell your friends that "I have an aunt with whom I live."

Regarding this usage, David Crystal's Encyclopedia notes:

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This usage is probably first introduced by John Dryden in the 17th century, and shows the influence of Latin grammar, where prepositions usually preceded nouns. It has never reflected colloquial practice in English, though in formal English the prescriptive rule tends to be followed. To alter someone's practice can be dangerous, as in Winston Churchill's famous reaction to secretarial changes made to his usage: 'This is the sort of English up with which I will not put.' (194)
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I've never come across "up with which" except this Winston Churchill's witty reaction!
It's interesting that, throughout history, many aspects of the English language has been influenced by Latin. It is by way of analogy with Latin that people feel confident about the English usage. Why? Because Latin was a prestigious model upon which English is based.

Works Cited:
Crystal, David. The Cambridge Encyclopedia of Language. 2nd ed. Cambridge: CUP, 1997.